File mq-notify-use-after-free.patch of Package glibc

Overview Repositories Revisions Requests Users Attributes Meta

File mq-notify-use-after-free.patch of Package glibc (Revision 7a3188f02333469e025fd634884b31f5)

Currently displaying revision 7a3188f02333469e025fd634884b31f5 , Show latest

From 42d359350510506b87101cf77202fefcbfc790cb Mon Sep 17 00:00:00 2001
From: Andreas Schwab <schwab@linux-m68k.org>
Date: Thu, 27 May 2021 12:49:47 +0200
Subject: [PATCH 1/2] Use __pthread_attr_copy in mq_notify (bug 27896)

Make a deep copy of the pthread attribute object to remove a potential
use-after-free issue.
 
  CVE-2021-33574: The mq_notify function has a potential use-after-free
  issue when using a notification type of SIGEV_THREAD and a thread
  attribute with a non-default affinity mask.

diff --git a/sysdeps/unix/sysv/linux/mq_notify.c b/sysdeps/unix/sysv/linux/mq_notify.c
index cc575a0cdd..f7ddfe5a6c 100644
--- a/sysdeps/unix/sysv/linux/mq_notify.c
+++ b/sysdeps/unix/sysv/linux/mq_notify.c
@@ -133,8 +133,11 @@ helper_thread (void *arg)
 	    (void) __pthread_barrier_wait (&notify_barrier);
 	}
       else if (data.raw[NOTIFY_COOKIE_LEN - 1] == NOTIFY_REMOVED)
-	/* The only state we keep is the copy of the thread attributes.  */
-	free (data.attr);
+	{
+	  /* The only state we keep is the copy of the thread attributes.  */
+	  pthread_attr_destroy (data.attr);
+	  free (data.attr);
+	}
     }
   return NULL;
 }
@@ -255,8 +258,7 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)
       if (data.attr == NULL)
 	return -1;
 
-      memcpy (data.attr, notification->sigev_notify_attributes,
-	      sizeof (pthread_attr_t));
+      __pthread_attr_copy (data.attr, notification->sigev_notify_attributes);
     }
 
   /* Construct the new request.  */
@@ -270,7 +272,10 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)
 
   /* If it failed, free the allocated memory.  */
   if (__glibc_unlikely (retval != 0))
-    free (data.attr);
+    {
+      pthread_attr_destroy (data.attr);
+      free (data.attr);
+    }
 
   return retval;
 }
-- 
2.31.1

From 217b6dc298156bdb0d6aea9ea93e7e394a5ff091 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Tue, 1 Jun 2021 17:51:41 +0200
Subject: [PATCH 2/2] Fix use of __pthread_attr_copy in mq_notify (bug 27896)

__pthread_attr_copy can fail and does not initialize the attribute
structure in that case.

If __pthread_attr_copy is never called and there is no allocated
attribute, pthread_attr_destroy should not be called, otherwise
there is a null pointer dereference in rt/tst-mqueue6.

Fixes commit 42d359350510506b87101cf77202fefcbfc790cb
("Use __pthread_attr_copy in mq_notify (bug 27896)").

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
---
 sysdeps/unix/sysv/linux/mq_notify.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/mq_notify.c b/sysdeps/unix/sysv/linux/mq_notify.c
index f7ddfe5a6c..6f46d29d1d 100644
--- a/sysdeps/unix/sysv/linux/mq_notify.c
+++ b/sysdeps/unix/sysv/linux/mq_notify.c
@@ -258,7 +258,14 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)
       if (data.attr == NULL)
 	return -1;
 
-      __pthread_attr_copy (data.attr, notification->sigev_notify_attributes);
+      int ret = __pthread_attr_copy (data.attr,
+				     notification->sigev_notify_attributes);
+      if (ret != 0)
+	{
+	  free (data.attr);
+	  __set_errno (ret);
+	  return -1;
+	}
     }
 
   /* Construct the new request.  */
@@ -271,7 +278,7 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)
   int retval = INLINE_SYSCALL (mq_notify, 2, mqdes, &se);
 
   /* If it failed, free the allocated memory.  */
-  if (__glibc_unlikely (retval != 0))
+  if (retval != 0 && data.attr != NULL)
     {
       pthread_attr_destroy (data.attr);
       free (data.attr);
-- 
2.31.1

Places

File mq-notify-use-after-free.patch of Package glibc (Revision 7a3188f02333469e025fd634884b31f5)

Places